Their siege was in response to a raid by immigration officials on Friday that led to six cleaners, alleged to be illegal workers, being deported and two being held in custody.

The cleaners, from South America, were part of a campaign to raise wages so that others like them could survive in London – the London Living Wage campaign.

Some students claim the university tipped off immigration officials. But the university denies this. Paul Webley, principal of Soas, said: "Contrary to some of the erroneous allegations being made, Friday's visit was not arranged or influenced by any member of staff at Soas."

The students' occupation ended this afternoon after the university agreed to write to the home secretary to request the cleaners be granted "exceptional leave" to stay in the UK.

Hanadi Katerji, secretary of the Soas student union, said: "We won some important victories with the management. It is the start of a long campaign for us. I'd like to see all staff brought in-house and given the London living wage."

The cleaners were employed by a contract company, ISS, which has denied any links between the "living wage" campaign and the immigration raid.

A UK Border Agency spokesperson said: 'We will not tolerate illegal working. It leads to the exploitation of illegal immigrants, who are frequently denied the minimum wage or forced to risk dangerous working conditions."